Light guides can be used to provide functional or decorative lighting. Functional lighting refers to lighting that is used for the purpose of illuminating an object or area to make the object or area more conspicuous. Decorative lighting refers to lighting that is used for aesthetic purposes. Often, light guides are used for both functional and decorative purposes.
A light source can be used to illuminate one or more light guides such that light is transmitted through the light guides via total internal reflection. Light guides may provide side lighting, in which light is emitted from the sides of the guides. In addition, light guides may provide end lighting, in which light is emitted from the end of the guides. A variety of different extraction techniques using notches or coating, for example, can be applied to the light guides to cause light to be emitted from the light guides in a controlled or random manner.
Lighting systems that implement light guides generally have a light source that illuminates the light guide. For example, incandescent light sources, florescent light sources, or light emitting diodes are often used to illuminate a light guide. The light source may reside in a light source assembly, also referred to as an illuminator. The light can be transmitted down the light guide, possibly changing colors or pulsating over time to provide the desired functional or decorative effect.
Light emitting diodes are particularly well suited for illuminating light guides because light emitting diodes are point-like light sources. Moreover, light emitting diodes use less energy than many other light source alternatives. Some light emitting diodes, however, have “batwing” radiation patterns in which the maximum luminous intensity of the light emitting diodes is angularly displaced. Therefore, conventional lighting systems that utilize light emitting diodes often utilize corrective optics to correct for the angular displacement of the radiation pattern and provide peak radiation intensity along a center axis of the light emitting diodes.